A gas turbine can generate a rotational power by driving a turbine with a high-temperature, high-pressure combustion gas which is produced by combustion of a fuel gas and compressed air supplied into a combustor. The combustion gas having driven the turbine is discharged to the atmosphere after conversion of dynamic pressure into a static pressure in a diffuser of an exhaust chamber.
In such a gas turbine, the temperature of the combustion gas supplied to the turbine is very high due to increased efficiency. Therefore, cooling is performed on almost all components of the turbine, and it is also necessary to reliably cool inside of the exhaust chamber.
The above-mentioned gas turbine having a cooling structure in the exhaust chamber is disclosed in, for example, Patent Document 1, in which the exhaust chamber of the gas turbine is installed with a casing wall and struts. The strut is arranged in plurality in a circumferential direction at predetermined intervals, and connected to a bearing case which is disposed inside the casing wall in a radial direction and houses a bearing supporting a rotor, and supports the bearing case on the casing wall. By supplying cooling air into the exhaust chamber through a cooling flow passage which is formed between the strut and the strut cover installed in an outer circumferential side of the strut, cooling of the components in the exhaust chamber, such as the diffuser, the strut, and the strut cover is performed.